The present invention concerns the technique of supplying a fluid product such as an extendable foamy, liquid, or gaseous product, by placing the product under adjusted pressure in a nozzle.
The technique for supplying a fluid at an adjusted pressure (see, for example, U.S. Pat. No. 3,873,258) proves especially advantageous with respect to a conventional fluid-spraying procedure, in order to produce foam-based, and thus expandable, objects in a size and at a density which remain constant in one or more directions. In fact, the pressure controls the expansion of the foam, and, therefore, the size of the object produced by extrusion.
The conventional state of the art encompasses two approaches:
1) Installation of a mechanical pressure regulator up-line form the nozzle. This procedure entails the following problems: PA1 2) Causing the nozzle opening to vary as a function of the pressure inside the nozzle (see U.S. Pat. No. 3,873,258). PA1 the nozzle is a gun, PA1 the means used to close and adjust the opening of the nozzle is a piston. PA1 pressurization of the material, PA1 feed of material to the nozzle through the line, PA1 measurement of the pressure of the material in the nozzle, PA1 comparison of the pressure as measured to the pressure value stored in memory in an electronic card, PA1 adjustment of the pressure of the material in the line by the electronic card acting on pressurization means.
the pressure regulator is bulky and thus difficult to install on a robot; PA2 it has dead spaces in which the product deteriorates over time and makes the constituent ineffective.
This approach comprises at least one tank from which a feed line extends, and at least one nozzle having means for closing and adjusting the opening of the nozzle, the device having an electrical control box incorporating a conventional electronic card. The electronic system continuously adjusts the opening of the nozzle in order to generate constant pressure, thereby making it possible to produce a constant flow rate, whatever the up-line pressure of the product.
This solution has the disadvantage of being bulky and extremely expensive.
In both cases, precise temperature control is necessary for products whose viscosity varies with temperature.